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 A242172 a(n) = 2^n*binomial((n + 1 + (n mod 2))/2, 1/2). 0
 1, 3, 6, 15, 30, 70, 140, 315, 630, 1386, 2772, 6006, 12012, 25740, 51480, 109395, 218790, 461890, 923780, 1939938, 3879876, 8112468, 16224936, 33801950, 67603900, 140408100, 280816200, 581690700, 1163381400, 2404321560, 4808643120, 9917826435, 19835652870 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS FORMULA a(2*n) = A002457(n). a(2*n+1) = A033876(n). a(2*n+2)/2 = a(2*n+1). Conjecture: (n+1)*a(n) -2*a(n-1) +4*(-n-1)*a(n-2)=0. - R. J. Mathar, May 11 2014 a(n) = A100071(n+2)/2. \\ Michel Marcus, Sep 14 2015 MAPLE a := n -> 2^n*binomial((n+1+(n mod 2))/2, 1/2); seq(a(n), n=0..29); CROSSREFS Cf. A100071, A002457, A033876. Sequence in context: A152232 A183038 A141023 * A126982 A256281 A034739 Adjacent sequences:  A242169 A242170 A242171 * A242173 A242174 A242175 KEYWORD nonn AUTHOR Peter Luschny, May 06 2014 STATUS approved

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Last modified January 20 11:01 EST 2020. Contains 331083 sequences. (Running on oeis4.)